Photographic objective.



nu. 660,202. Patented octgza, uson.

' P. HuooLPn.

PHOTBSRAPHIC DBJECTWE.

(APMM Mld JAI. L 1m) (lo Ichi.)

UNITED STATES PATENT; OFFICE.v

. PAUL RUDOLPH, OF JENA, GERMANY; ASSIGNOR TO THE FIRM CARL ZEISS;

OF SAME PLACE. l

- PHOTOGRAPH@ OBJ 'EO-rive;

.srscrrrcsnon forming pm. of maar. ruses NQ. 660.202, man october' as,1906; 1 Anuman ma :muy 2,1900. sum so. 1an. ur um.,

To all 1 0/tom. it may concern.:

Be it known that I, PAUL RUDCLPH, doctor of philosophy, a subject of theDuke of Saxe- Alt-enburg, residing at Jena,v in the Grand Duchy ofSaxe-Weimar-Eisenach, German Empire, have invented' a new and usefulPh`o tographic Objective, of which the following is a specification. y

The photographic objective hereinafter dero 4scribed hasv been devisedfor -purposes which require a large aperture and ananastigmatically-flattened field foraeomparat-ively large angle. Theadvantage of this objective as compared v' th combinations hithertoknown t5 for similar purposes-for instance, the objectives descri hed inPatent No. 444,714 and like anastigmaticconstructions-is that the choiceof glasses is hardly limited and less lenses are necessary to obtaingood spherical correczo tion even in types of high aperture. This doubleadvantage of the new objective is duc to the use of two pairs of glasssurfaces, each pair consisting of two surfaces which face oneanother-that is to say, which belong to z5 two consecutive lenses -andare separated by an air-space, but not by the diaphragm of the system,and the powers of both pairs being of oppositesign.

lf fn] and n2 be the refractive indices of the 3o two consecutive lensesand r, and n the radii of curvature of the glass surfaces facing oneanother, the power of such a pair of surfaces is given by 11,-1 '11,-1Ti Tk the axial thickness of the air-space between both facing surfacesbeing supposed to be negligible. Y

4o There exist already several photographic objectives having two pairsof facing glass Surfaces separated by air; but the powers of these pairsare both positive or both negative.

It may be inferred from Fig. 3 of Patent No.

583,336, relating to the so-called Planar, that the two pairs of facingglass surfaces are the surfaces r" 'r3' and r, a', ofthe lenses L3 L2and L2 La, respectively. The sign of the power of each pair ispositive.` Another con- 5o struction of this kind has been described inthe English specification No. 12,859, A. D. 1898. This ojective iscomposed of four separate parts and contains, according to. the datagiven in M. von Rohrs Theorie und Geschichte des PhotographischenObjective, 5s

(Theory and History of the Photographic Objective,)` p. y392, two pairsof facing glass surfaces, each of which pairs has a negative power.

The effect of combining two pairs of facl 6o.

ing surfaces of Vopposite power is similar to th'e result obtained inthe objective described in Patent No. 444,714 by the opposite signprescribed for the difference between the refractive indices of thecrown and flint lenses in the cemented components of a doublet. Thepairs of facing surfaces produce, in accordance with the signs of theirpowers, as tigmatic differences of opposite character, so that inaddition to spherical correction of y. the whole system and flatteningof the image astigmatism may fully be corrected. In the former objectivethe maximum difference of the refractive indices of the lensescementedtogether was (with regard to practical usefulness of the glasses) 1.63-0.13. In the present objective, however,v 'the difference of therefractive indices belonging toeach of the facing glass surfaces willamount to 1.5()- LOO 0.5 0 even in the most unfavorable case. 8o It isfurther to be considered that vwhen the present objective has the samenumber of lenses as the former its number of elements available forcorrection is increased, so that the present objective when consistingof four lenses presents a surplus of two radii and two air-spaces. Y

From the foregoing it will be understood that the adoption of the newtype of objective will Vresult either in larger apertures, the sphericalcorrections remaining of the same quality, or, when the apertures areunaltered, in improved spherical corrections.

Besides the two pairs of facing glass surfaces of opposite sign thewell-known means of correction may beemployed at will, and inconsequence thereof the new objective may consist o'f single lenses aswell as of cementedlens systems. Moreover, it is an essential feature ofthe invention that the selection of kinds of glass is nearly unlimited,so that l shown, which has been developed from the glasses whichdiminish the secondary specdoublet represented in Fig. 3 by substituttrnm may be used, although. their optical ing two elements L3' and L3",cemented toproperties vary in very narrow limits only. 4gether for thelens L3. Example 3,' given be- 7 5 The features of the invention maybereallow and showing detailed data of construe ized either in simpleobjectives. (objectives tion, refers to the same. Fig. 4. In thisexhaving the diaphragm behind or in f ront of -ample L; and L3 areground from glasses them) or iu doublets, (objectives in which havingthe same refraction but different disl the diaphragm is placed withinthe system.) pei-sion, so as to chromatically correct the 1o In theannexed-drawings, Figure 1 reprewhole system.

sents a simple objective constructed accord- Finally, in Fig. 5 a.construction is repreing to the invention. Fig. 2 represents a sented inwhich for the lens L, of Fig. 3 a doublet, one of the two components ofwhich compound consisting of L,' and L," has been is constructedaccording to the invention. substituted. In the Example 4, which gives 815 Fig. 3 'represents a doublet constructed acdetailed data ofconstruction in reference to cording to the invention. Fig. 4 representsFig. 5, glasses of different dispersion and difanother doubletconstructed according to the ferentrefraction have been selected,bymeans invention. Fig. 5 represents a third doublet of which thechromatic correction as well as separately, as shown in Fig. 1. One pairof jectives constructed according to the invenfaciug glass surfaces isformed by the surtion the letters L, L2 denote the lenses; d1 rfaces r,r, of the lenses L, L2 and the other by their axial thicknesses; r, r2,the radii of cur- 9 t the surfaces 1'4 T5 of tl-.c lenses L., L3. Forvature of their spherical surfaces; b, 1) the l each of the single'elements L,`L2 L.3 a comdistances between the diaphragm andthe adpounddens or a non-cemented-lens system jacent lens vertices; l, 1. theaxial thickmaybe substituted,whereby the construction nesses of theair-spaces between two lenses, of the simple objective becomes more orless (the d'istancesbetween twolensesj' The radii, 95 i 3o complicated.vSuch a simple objective may thicknesses, diameters, and distances areexl also advantageously be used as a component pressed by proportionalnumbers, the unity of unsyx'nmetrical as well as hemiorholo symof whichis the focal length of the entire ob# metrical donblets. The mostprimitive kind jective. By simply multiplying these numof anunsymmetrical doublet, acomponent of bers with the focal length requiredin each I0* which is a simple objective constructed accase the data ofconstruction for any objeccording to the invention, is shown in Fig. 2.tive wanted will be obtained. The different 1t consists of four lensesL, LzL3 L the back kinds of glass are determined by their refraccomponent Lrl-LlL4 being the simple obtive indices nu, m, and nm,relating to the jective shown in Fig. 1; butit will be nnder- D-line andthe F-line'of the solar spectrum w` 4o stood )that the sim ple objectivemay also be and to the Hy-line of the hydrogen spectrum,

used as the front component of thedonblet.

The most primitive doublet, which in its D tommy is const luledaccording ,t0 he in' the relative dispersive power of the kind ofvention, has two lenses in front of the diaglass, A?, being given forthe interval be. n Y Phfagm and W0 lenses behind it as Show tween D andHy, whereas by the quotients in Fig. 3, the two' pairs of facingsurfaces bel ing placed'on diterent sides of the diaphragm.

constructed according to the invention. the diminution of the sphericalzones are ob- 85 zo The most primitive simple objective contained. sistsof three single lenses L, L2 L, placed In the following numericalexamples of obrespectively. The value of nfn indicates The surfaces r2r, of the lenses L, Lgform the Eff-93 one pair having positive power andthe surd "Gff'n" 5o faces r, r, of the lenses Ls L, the other pair anhaving negative power. The lenses L, L, L, '51:2'. 3 L, may be singlelenses, as shown, orcotn- 7101",

pound lenses. 1t will be preferable to substitnte compound for some ofthe single the increase of the dispersion in the considlenses either forthe purpose of remaining ered interval is shown. within certainlimits astothe choice of glasses Example 1, Fig. 1: Spherically and chroor forobtaining certain effects as regards the matcally corrected simpleobjective in which correction of chromatic or spherical aberratheanastigmatc liatness of the field is nearly tions. According to theparticular purposes obtained: The objective consists of three 1k 6o ofeach doublet the elements of such a comsingle lenses L, L2 La, of whichL, is a dis-y posit-e lens maybe madeof glasses having the persing-lens,while L2 and L3 are collective same refraction 'and different dispersionor lenses. The two pairs cffacing glass surfaces the same dispersion anddifferent refraction consist ofthe surfaces lr, r, of the lenses L, L,or different refraction and different disperand r, r, of the lenses L,lThe focal length x sion. is 1. The highest relative aperture available.In Fig. 4 a more complicated doublet is is 0.125.

Powers of the Pofs of Facing Surfqesfcr y p focal length is'l.

Thiel-messes and Radu" disances. r1:-0.145 01:0.015 r2. '0.967 1:000723:-0339 l :0. 010 r4:0.139 1:0015 r.:-2.418' 1A :0.005 r6: 0.214 i:0.019 Kinds of Gloss.-

1 5L.. L.. L..

n., 1.57740 1.51790 1.61232 11, 1.53734 1.52396 1.61996 n... 1.595711.52834 1.62614 Lx v n f1 0.03171 0.02112 0.02257 n .2L-d2 9.5.43 0.554.``0.553 1 gif-nn "I Y 'nn-'no1 l' 'v Example 2, Fig. 3: Spherically andchroinatically corrected doublet having an anas-. tigmaticallyflattened.field: The objective consists of fonrsingle lenses Lx LL3L Ll and L.being collective lenses and L2 and Ls dis.- persive lenses. The twopairs of facing glass 35 surfaces consist of the surfaces 'rz r3 of thelenses L1 Lzand r6 lr., of the lenses L3 L4. The

rlhe highest relative aperture available is 0.106.

Rad; Thiclmesses and dzsla-nces. lr,:+0.207 711:0.035 y Y 'r2=1.174 1:0.021 7.,::0463 :0.014 r.:+0.211 51:0.021 5:-.0.345 0,:0021 76:-0463@:0.014 17=-1.726 ggf-0.001 2,.: 0.314 .:0.035

Kinds of Glass. L.. L, 1.,. L.. n., 1.5.9119 1.57070 1.51147 1.61091 n..1.59900 1.53953 1.51710 1.61352 51..; 1.60344 1.59779 1.52159 1.02469ff-1- 0.02072 0.03120 0.01979 0.02226 0.556 0.544 0.556 0.552 "U1-nr l'P- '0.444 0.457 0.444 0.448- 'HG1-'nn Powers of the Pairs of FacingSurfaces for un.

Example 3, Fig.. 4: Spherically and chromatically corrected doublethaving ananastiglnatically-fiatt-ened field and a. diminished secondaryspectrum: The objective consists o ffive lenses L, L3' L L4, of whichLs' and L3" are cemented together. Ll and L. are collective lenses.lenses. The two pairs of facing surfaces consist of the surfaces lr2 r,of the lenses 1.1L2 and 7'., lr8 0f the lenses L," L.. Thev diaphragm islocated between the lenses L2 and L,. The focal distance is 1'. Thehighest'. relative ap- L2 and LE'+L are dispersive4 Powers of the Pairsof Facing Surfaces for 14D.

im: 1119-71 :min-M96 Example. 4, Fig. 5: Spherically and chromaticallycorrected doublet having an anastigmaticallyattened field: The objectiveconsists of three collective lenses Ll L, L4+L"' and adispersive lensL2. The two pairs of facing glass surfaces consist of the surfaces 7,1-,of the lenses Ll L2 and 7', 77 of theV lenses L3 L". The diaphragm isplaced between the lenses L2 antilla. The focal length is 1. The'highest relative aperture available is 0.25.

Rad Thcknesses and dstafwes. riss-0.281 dl `:0.047 Tfr-1.874 :0.023r,:-0.628 :0.019 'Qi-+0286. b1 :0.038 T5: 0.469 b, :0.030 r.:-0.422 d,:0.019 4F-2.343 5 :0.002 r,:+0.506 Y :0.014 Y1', =0.506 d"=0.033

Emea .GLY f Kinds of Glass.

L,=L"'. L2=L8=L n., 1.61091 1.57311 si',y 1.61852 1.58264` 'nel 1.624691.59063 An OLO2256 0.03057 naw-1 ,nn 0.552 0.544

Pow'ers of the Pairs qfFaci'ng Surfaesfof ne; 0.61091 0.57311 Whst Iclsim'ss my invention, and desire to secure by Letters Patent oftheUnited States, is y v A spherically and chromatically correctedobjective having an anastigmfiticallyfiattened field and consisting ofat least tb ree sep# erste lenses so' as to include at least twoairspaces,in which objective two of the' air-spaces are separated fromtbe diaphragm each by at least one lens and confined one -by a pair ofglass sui-facesthe power of which is positive and the other by a pair ofglass surfaces theV power of which is negsti've, essentially as de;scribed. l

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

- PAUL RUDOLPH.

Witnesses: y n' PAUL Tmcnmx, LINA Jua.

